- A method for preparing prilocaine hydrochloride
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The invention relates to a synthetic process of anesthetic, in particular to a method for preparing propitocaine hydrochloride. The method includes the following steps that a, ortho-toluidine is added into dichloromethane, alpha-propionyl chloride is dropwise added at the room temperature, and the reaction lasts for 2-3 h at the temperature of 15 DEG C-25 DEG C, acid solution washing is performed on the obtained reaction liquid, then, aqueous alkali washing is performed on the obtained reaction liquid, water is added to an organic layer to separate solids out, and then propitocaine hydrochloride midbody is obtained through filtration; b, the propitocaine hydrochloride midbody obtained in the step a is added into n-propylamine, reflux is heated for 5-7 h, after the reaction is ended, concentrated hydrochloric acid is added to adjust the PH to be 1-2, white solids are separated out and are refined through ethyl alcohol of 95%, and therefore the propitocaine hydrochloride is obtained. An acetone solvent which is unfriendly to the environment and has hypotoxicity in a traditional method is replaced by the commonly used solvent dichloromethane which is basically free of toxic, and therefore environment-friendly industrial mass production becomes possible on the premise of not affecting the yield.
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Paragraph 0051; 0052
(2017/03/14)
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- Preparation method of prilocaine base
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The invention discloses a preparation method of prilocaine base. The method comprises the following steps: directly condensing 2-chloropropionic acid (formula V) and o-toluidine (formula IV) in the presence of chlorinated 4-(4,6-dimethoxy-1,3,5-triazine-2-yl)-4-methylmorpholine to obtain N-(2-methyl phenyl)-2-chloride propionamide (formula III); reacting the N-(2-methyl phenyl)-2-chloride propionamide (formula III) with n-propylamine (formula II) in an acetone solvent in the presence of granular potassium carbonate to obtain a crude product of prilocaine base; and refining the prilocaine base to obtain medicine-grade prilocaine base (formula I). The method disclosed by the invention overcomes the shortcomings of the prior art and has the advantages of mild reaction conditions, no pollution, no equipment corrosion, good quality, high yield and convenient operation and is suitable for industrial production.
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Paragraph 0017
(2016/10/31)
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- Kinetics of degradation of 4-imidazolidinone prodrug types obtained from reacting prilocaine with formaldehyde and acetaldehyde
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The kinetics of decomposition of 4-imidazolidinone prodrug types obtained by reacting prilocaine (I) with formaldehyde and acetaldehyde has been studied in aqueous solution in the pH range 1-7.4 at 60 and 37°C, respectively. At pHA plot of the logarithm of the apparent first-order rate constants for hydrolysis of II against pH resulted in a sigmoidal-shaped pH-rate profile characteristic for the hydrolysis of many N-Mannich bases. A half-life at pH 7.4 (60°C) of 6.9h for compound II was calculated. Compared to II the 4-imidazolidinone derived from acetaldehyde (III) exhibited enhanced instability in aqueous buffer solutions. The decomposition was followed at 37°C monitoring the decrease in concentration of intact (III). At acidic pH the reactions displayed strict first-order kinetics and the disappearance of III was accompanied by a concomitant formation of I. At pH 7.4, the rate data also applied reasonably well to first-order kinetics despite the observation that small amounts of III was formed at pH 7.4 from a solution containing equimolar concentrations of acetaldehyde and prilocaine (10 -4M). In case of III, a bell-shaped pH-rate profile was obtained by plotting the logarithm of the pseudo-first-order rate constants against pH indicating the involvement of a kinetically significant intermediate in the reaction pathway and a change of the rate-limiting step in the overall reaction with pH. For the stability studies performed at pH 6.9 and 7.4 product analysis revealed that parallel to formation of (I) an unknown compound (X) emerged. Compared to III, compound X is hydrolysed to give I at a slower rate (t 50%=30h at 37°C). Based on LC-MS data it is suggested that (X) is an isomeric form of III, which may exist in four diastereomeric forms. Thus, at physiological pH an initial relatively fast regeneration of I from III is to be expected followed by a slower drug activation resulting from hydrolysis of the isomeric form of III.
- Larsen, Susan Weng,Sidenius, Martin,Ankersen, Michael,Larsen, Claus
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p. 233 - 240
(2007/10/03)
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